From the east:
Stay on the M4 to the end and then follow the A48 towards Carmarthen. Follow the A40 (W) and St Clears. At the St Clears roundabout stay on the A40 towards Haverfordwest. There are also brown signs to Oakwood. Stay on the A40 until you reach the left turn off for the A4075 to Tenby (and Oakwood). Turn here, go past Oakwood and just after this is a junction with a right turn to Lawrenny. After approximately 1.5 miles after the sharp left hand bend take a left turn (looks straight on) which is signed to Lawrenny. At the T-junction turn right, take the next right turn and at the next T-junction turn left. Knowles Farmhouse is about 1 mile down here on the right hand side. If you come to a crossroads you've gone too far.
Knowles Farm House is set above the Cleddau river in Britain's only Coastal National Park. It is just 6 miles from the main A40 but it feels like another world.